Wet friction material

Abstract

There is disclosed a wet friction material which comprises 5 to 40% by weight of a thermosetting resin as a binder component with the balance being a filler, wherein the filler includes at least a rubber and an exfoliated graphite.

We claim: 
     
       1. A friction material comprising 5 to 40% by weight of a thermosetting resin as a binder component with a balance being a filler, wherein said filler includes at least an exfoliated graphite, said exfoliated graphite being impregnated or coated with a rubber prior to being combined with said thermosetting resin. 
     
     
       2. The wet friction material according to claim 1, wherein said filler further comprises a porous pulp granulated powder partially bound with the thermosetting resin. 
     
     
       3. The wet friction material according to claim 2, wherein said porous pulp granulated powder bound partially with a thermosetting resin has a porosity of 20 to 70%. 
     
     
       4. The wet friction material according to claim 1, wherein the amount of the exfoliated graphite impregnated or coated with a rubber is 1 to 60% by weight. 
     
     
       5. The wet friction material according to claim 2, wherein the amount of the exfoliated graphite impregnated or coated with a rubber is 1 to 60% by weight. 
     
     
       6. The wet friction material according to claim 3, wherein the amount of the exfoliated graphite impregnated or coated with a rubber is 1 to 60% by weight. 
     
     
       7. A friction material according to claim 4 wherein said exfoliated graphite comprises graphite crystals formed in laminated hexagonal-shaped planes of natural or artificial graphite layers, wherein the interlayer distance of said crystals is expanded ranging from several fold to several hundred fold. 
     
     
       8. The friction material according to claim 7, wherein the interlayer distance of said crystals is expanded ranging from two-fold to two hundred-fold. 
     
     
       9. The friction material according to claim 2, wherein said porous pulp granulated powder comprises cellulose fibers. 
     
     
       10. The friction material according to claim 1, wherein said thermosetting resin is selected from the group consisting of phenol resin and polyimide resin. 
     
     
       11. The friction material according to claim 1, wherein said rubber is selected from the group consisting of natural rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, acryl rubber, thiocol rubber, urethane rubber, epichllorohydrin rubber, silicone rubber, fluorine rubber and a hydrogenated or modified rubber thereof.